Jetta stalls when idling in cold weather

Hi,

Maybe someone can help me with this. I have a 98 Jetta. For the past week the weather has been very cold with the temperature around 0 degrees. The other day the engine wouldn't turn over, so I replaced the battery. The engine starts fine now but shuts down when idling. If I sit in the car with my foot on the gas it will run, but even after warming up, it still stalls when slowing down going around a corner or stopping at a light. Any ideas or suggestions? Maybe I knocked something out of place when putting the battery in? Thanks!